1. Field of the Invention
The present invention relates to addressing of network traffic, and more specifically, to addressing for routing various traffic across public networks.
2. Acronyms
The written description provided herein contains acronyms that refer to various telecommunications services, components and techniques, as well as features relating to the present invention. Although some of these acronyms are known, use of these acronyms is not strictly standardized in the art. For purposes of the written description herein, the acronyms are defined as follows:                ASP—ATM Service Provider (a CSP)        ADP—ATM Destination Point (address)        ATI—ATM Terminating Interface (address)        ATM—Asynchronous Transfer Mode        CO—Central Office        CPN—Compatible Public Network        CSP—CPN Service Provider        DAP—Directory Access Protocol        DCC—Data Country Code (ISO 3166)        DNS—Domain Name System (or Server)        E.164—ITU-T Recommendation E.164, 05/1997        IAR—Inter-ASP Routing        ICD—International Code Designator        IP—Internet Protocol        ISP—Internet Service Provider        LAN—Local Area Network        LDAP—Lightweight Directory Access Protocol        MPLS—Multiprotocol Label Switching        NAT—Network Address Translation        NS—Naming System (generic)        PNNI—Public Network—Network Interface        RR—Resource Record        SVC—Switched Virtual Circuit        SOA—Source of Authority        TAS—Transported Address Stack        TAS IE—Transported Address Stack Information Element        UNI—User-Network Interface        VPN—Virtual Private Network        VTOA—Voice Trunking Over ATM        WAN—Wide Area Network        
3. Background Information
Traditionally, large-scale broadband networks, often telecommunications networks, perform routing and addressing in a “single-level” fashion. An Asynchronous Transfer Mode network (ATM) is one example of a kind of large-scale broadband network using single-level addressing. When single-level addressing and routing is employed, the calling party and called party must use addresses that have topological significance to the network(s) carrying the traffic. That is, routing according to the address will direct the traffic according to the positional relationship (i.e., in terms of network topology, not necessarily physical topology) of the calling and called parties. Single-level addressing is not scalable to a globally based network.
A monolithic network, public or private, has only one addressing scheme. From any edge of the network, a call can reach any nodes attached to the monolithic network at another edge because there is no address ambiguity. Routing within a monolithic network employs unique addresses that are both native and certain. A compatible public network, if operated under a single addressing scheme, can be treated as a monolithic network. In this case, the compatible public network and users are using the same (public) addressing scheme for routing (port designation) and for service (user designation). Under this scenario, compatible public network switches must propagate signals corresponding to users (possibly represented as end systems or data terminals) throughout the compatible public network's routing mechanism. Although small-scale independent networks can be designed and operated under a monolithic model, this is not the preferred case for large public networks servicing WAN applications.
Where support of multiple addressing schemes is required, a compatible public network may be required to build multiple or parallel monolithic networks that each run on independent addressing. When the demand is not high, a few parallel networks may be established, but as a multiplicity of customers require independent addressing, the number of parallel networks that must be established becomes impractical. Even though a compatible public network may own and operate versatile switches that support more than one addressing scheme, the concurrent operation of independently addressed networks on the same switches, from the addressing perspective, is considered the operation of multiple monolithic networks.
Problems also arise on the user side, where unnecessary confusion and barriers are placed in the overall system, for example, when user A trying to connect to user B must ensure that the respective public networks to which the parties are connected have a compatible addressing scheme and connectivity. Accordingly, from the perspective of a compatible public network, running multiple monolithic networks is not an economical solution.
The issue of multiple monolithic networks becomes more complicated when compatible public networks build additional networks as “islands” connected to the parent network, but with different native addressing schemes. These island networks, usually built as monolithic networks, may use vastly different addressing from each other and from the parent compatible public network. The compatible public network would, of course, require all users connecting to the island networks to use the same addressing scheme as the island. Island-connected users who use different addressing schemes from one another find that interconnections between islands are difficult even thought the interconnection is within the same compatible public network. Naturally, since even intra-public-network island interconnections are challenging, “global” inter-public-network island interconnections are proportionately more difficult. Not only the addressing schemes vary, but also translations between addressing schemes (even when the translation is from and to the same scheme) may also vary, since each compatible public network may choose a proprietary or non-standard translation. Global inter-public-network connections are made more difficult and may become fragmented.
Ideally, the compatible public network should support multiple services and multiple addresses. However, building a carrier scale broadband Wide Area Network (WAN) requires significant resources (engineering, equipment, support, etc.). As noted, it is not considered economical for compatible public networks to build multiple networks in parallel using different addressing schemes. If communication is difficult or impossible between network islands, services are not fully functional, and therefore not attractive to potential users. In this regard, each compatible public network would be better served with just one broadband backbone network that is capable of supporting all possible services, but that is indifferent as to addressing requirements that those services may have. Services capable of independence from their own addressing scheme should be able to communicate with each other when the addressing scheme is decoupled from the functionality of the services.